Measurements of mass and volume flow rates of fluid through a conduit are a part of operations in the oil and gas industry. When the ownership of fluid changes hands (custody transfer), a high integrity system that provides reliable flow data with minimal uncertainty is desirable.
Flow meters such as ultrasonic, turbine, and coriolis provide parametric data such as volume flow rate, flow velocity, and mass flow rate, while temperature, pressure, and differential pressure transmitters measure parametric data such as fluid temperature, differential pressure across an orifice, and static pressure. The parametric data may be used to derive a number of flow variables such as discharge coefficient, expansion factor, and fluid density and viscosity. Also, the parametric data may be used in a flow calculation equation to determine the fluid flow rate (if not determined directly by virtue of the meter used) and the total flow volume.
While such measurements and flow rate calculations have inherent inaccuracies, the precise measurement of fluid properties is necessitated in order to avoid improperly charging for the transfer of fluid. Currently, static error calculations are performed in an attempt to quantify the uncertainty in measurement. However, static error calculations are based on worse case scenarios, and the delay in such calculations lessens their usefulness.